I, but not just I for there are at least three other people trying to do this thing right now, am trying to put on a USB .ISOs of XP Pro, Windows 7 (64-bit) and HBCD as a sort of ultimate technician's tool.I can get Hiren's to work, or I can get the OSes to work, but never both at the same time.

Thoughts?

I've tried Rufus, YUMI, DaemonTools, XBoot and a few other things in all sorts of combinations.I'd also rather not have to mess about with DOS if at all possible.

you must partition the flash drive first. if you dont know what that is, think of it like creating a C, D, and E drive for a hard disk. they look like three different disks, but they all belong to the same physical drive. so if you split your USB drive in to three partitions, you can then install one ISO to each partition, and then whenever you boot from the USB drive, you should get the option to select one of the OSes to boot from.

you need to do this because each system must be isolated from the others.